The assembly of optical relay systems within flexible tubes is known in the art. For example, U.S. Pat. No. 7,530,945 to Rudischhauser et al. describes a method for assembling an endoscope having an optical system with several components that are at least partially surrounded by a tube made of both a transparent and a shrunk material. The method includes introducing the optical components into the tube of transparent and shrinkable material to form a unit, followed by shrinking the shrinkable material of the tube for fixing the position of the components contained within the tube relative to one another. To ensure the proper positioning of the components relative to one another, the components are inspected through the transparent shrunk material of the shrunk tube. After proper positioning of the components is confirmed, the unit composed of the shrunk tube and the components contained therein is introduced into a tubular shaft of the endoscope.
U.S. Pat. No. 8,819,913 to Bodor et al. describes a method of assembling an optical relay system including forming a line of optical components within an optical component aligning groove of a first base member, axially aligning a cylinder with the aligning groove of the first base member, detachably coupling the cylinder to the first base member and directing the line of optical components from the optical component receiving groove into the cylinder. The cylinder, the line of optical components and a shrinkable tube which has previously been placed around the cylinder are then detached from the first base member and positioned within a cylinder receiving groove of a second base member. With axial movement of the cylinder restricted within the cylinder receiving groove, the line of optical components is pushed out the cylinder and into the shrinkable tube which slides off of the cylinder by virtue of its constriction about a distal end of the line of optical components. The line of optical components and shrinkable tube then are advanced along the cylinder receiving groove and through a heating area where the shrinkable tube is shrunk about the line of optical components. To ensure axial compression upon the line of optical components within the shrinkable tube, a tension device located upstream of the heating area applies pressure on the shrink tube as it and the line of optical components are advanced long the cylinder receiving groove thereby causing the tube to stretch axially while the shrinkable tube is heated and shrunk radially about the line of optics.